Dromaeosauridae
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{{Taxobox
| name = Dromaeosaurids
| fossil_range = [[Jurassic]] - [[Cretaceous]]
| image = Amnh30.jpg
| image_width = 250px
| image_caption = Model of ''[[Microraptor]]'' at the<br>[[American Museum of Natural History]]
| regnum = [[Animal]]ia
| phylum = [[Chordate|Chordata]]
| classis = [[Reptile|Sauropsida]]
| superordo = [[Dinosaur]]ia
| ordo = [[Saurischia]]
| subordo = [[Theropoda]]
| infraordo = [[Deinonychosauria]]
| familia = '''Dromaeosauridae'''
| familia_authority = Matthew & [[Barnum Brown|Brown]], 1922
| subdivision_ranks = [[Family (biology)|Subfamilies]]
| subdivision =
[[Dromaeosaurinae]]<br/>
[[Microraptorinae]]<br/>
[[Unenlagiinae]]<br/>
[[Velociraptorinae]]<br/>
}}
'''Dromaeosauridae''' is a family of [[bird]]-like [[theropod]] [[dinosaur]]s. They were small to medium - sized, feathered [[carnivore]]s that flourished in the [[Cretaceous]] [[Period (geology)|Period]]. In informal usage they are often called "[[raptors]]" (after ''[[Velociraptor]]''), a term popularized by the film ''[[Jurassic Park (film)|Jurassic Park]]''. The name Dromaeosauridae means 'running lizards', from [[Ancient Greek|Greek]] ''dromeus'' (''δρομευς'') meaning 'runner' and ''sauros'' (''σαυρος'') meaning 'lizard'.
Dromaeosaurid fossils have been found in [[North America]], [[Europe]], [[North Africa]], [[Japan]], [[China]], [[Mongolia]], [[Madagascar]], [[Argentina]], and [[Antarctica]].<ref name="caseetal2007">Case, J.A., Martin, J.E., and Reguero, M. (2007). "A dromaeosaur from the Maastrichtian of James Ross Island and the Late Cretaceous Antarctic dinosaur fauna." Pp. 1-4 in Cooper, A., Raymond, C., and Team, I.E. (eds.), ''Antarctica: a Keystone in a Changing World -- Online Proceedings for the Tenth International Symposium on Antarctic Earth Sciences'', U.S. Geological Survey Open-File Report 2007-1047, SRP 083. U.S. Geological Survey, Washington, D.C.</ref> They first appeared in the mid-Jurassic Period ([[Bathonian]] stage, 167 [[million years ago]]) and survived until the end of the Cretaceous ([[Maastrichtian]] stage, 65.5 ma), existing for over 100 million years, up until the [[Cretaceous-Tertiary extinction event]]. The presence of dromaeosaurs as early as the mid-Jurassic has been confirmed by the discovery of isolated fossil teeth, though no dromaeosaurid body fossils have been found from this period.<ref name="metcalfetal1992">{{cite journal | author = Metcalf, S.J., Vaughan, R.F., Benton, M.J., Cole, J., Simms, M.J. and Dartnall, D.L. | year = 1992 | title = A new Bathonian (Middle Jurassic) microvertebrate site, within the Chipping Norton Limestone Formation at Hornsleaslow Quarry, Gloucestershire | journal = Proceedings of the Geologists’ Association | volume = 103 | pages = 321–342 }}</ref>
==Characteristics==
===Body plan===
[[Image:Dromaeosauridae.JPG|thumb|left|Dromaeosaurid fossil displayed in Hong Kong Science Museum.]]
The distinctive dromaeosaurid [[body plan|bauplan]] helped to rekindle theories that dinosaurs may have been active, fast, and closely related to birds. [[Robert Bakker]]’s illustration for [[John Ostrom]]’s 1969 monograph,<ref name="ostrom1969"/> showing the dromaeosaurid ''[[Deinonychus]]'' in a fast run, is among the most influential paleontological reconstructions in history.<ref name="Paul06">Paul, Gregory S. (2006) "Drawing Dinosaurs"(2006). "Geotimes", January 2006. http://www.geotimes.org/jan06/feature_drawingdinos.html</ref> The dromaeosaurid body plan includes a relatively large skull, serrated teeth, narrow snout, and forward-facing eyes which indicate some degree of binocular vision.<ref name="Makovicky05">Makovicky, Peter J., Apesteguía, Sebastián & Agnolín, Federico L. (2005). "The earliest dromaeosaurid theropod from South America". ''Nature'', 437: 1007–1011. doi:10.1038/nature03996</ref> Dromaeosaurids, like most other theropods, had a moderately long S-curved neck, and their trunk was relatively short and deep. Like other [[maniraptora| maniraptorans]], they had long arms that could be folded against the body in some species, and relatively large hands with three long fingers (the middle finger being the longest and the first finger being the shortest) ending in large claws.<ref name ="dinosauria04">{{cite book|title=The Dinosauria |edition=2nd edition |year=2004 |chapter= Dromaeosauridae |editor=Weishampel, D.B., Dodson, P., Osmólska, H. |author=Norell, M.A., and Makovicky, P.J. |pages=196-210| location=Berkeley|publisher=University of California Press|isbn= 0-520-24209-2}}</ref> The dromaeosaurid hip structure featured a characteristiclly large pubic boot projecting beneath the base of the tail. Dromaeosaurid feet bore a large, recurved claw on the second toe. Their tails were slender, with long, low, vertebrae lacking transverse process and neural spines after the 14th caudal vertebra.<ref name="dinosauria04"/>
It is now known that at least some, and probably all, dromaeosaurids were covered in feathers, including large, vaned, wing and tail feathers. This development, first hypothesized in the mid-late 1980s and confirmed by fossil discoveries in 1999, represents a significant change in the way dromaeosaurids have historically been depicted in art and film (see “Feathers” below).
====Diagnosis====
Dromaeosaurs are diagnosed by the following features; short T-shaped [[frontal]]s that form the [[rostral]] boundary of the [[supratemporal fenestra]]; a caudolateral overhanging shelf of the [[squamosal]]; a lateral process of the [[quadrate]] that contacts the [[quadratojugal]]; raised, stalked, [[parapophyses]] on the [[dorsal vertebra]]e, a modified pedal digit II; [[Chevron (insignia)|chevrons]] and [[prezygapophyses]] of the [[caudal vertebrae]] elongate and spanning several vertebrae; the presence of a [[subglenoid fossa]] on the [[coracoid]].<ref name="dinosauria04"/>
====The dromaeosaurid foot====
Like other theropods, dromaeosaurids were bipedal; they walked on their hind legs. However, whereas other theropods walked with three toes contacting the ground, fossilized footprint tracks show that dromaeosaurids apparently held the second toe off the ground in a hyperextended position, with only the third and fourth toes bearing the weight of the animal. This is called functional didactyly.<ref name="Lietal2007">{{cite journal | first=Rihui | last=Li | coauthors= Lockley, M.G., Makovicky, P.J., Matsukawa, M., Norell, M.A., Harris, J.D. and Liu, M.| title=Behavioral and faunal implications of Early Cretaceous deinonychosaur trackways from China | date=2007 | publisher= | url =http://www.springerlink.com/content/v1u455854212404r/ | work =Naturwissenschaften | pages = | accessdate = | language = }}</ref> The "retracted" second toe bore an unusually large, curved sickle-shaped claw, which is thought to have been used in killing prey (see "Predatory behavior" below).
====The dromaeosaurid tail====
Dromaeosaurids had long tails. Most of the tail vertebrae bear bony, rod-like extensions, as well as bony tendons in some species. In his study of ''[[Deinonychus]]'', Ostrom proposed that these features stiffened the tail so that it could only flex at the base, and the whole tail would then move as a single, rigid, lever.<ref name="ostrom1969">{{cite journal|last=Ostrom|first=J. H.|year=1969|title=Osteology of ''Deinonychus antirrhopus'', an unusual theropod from the Lower Cretaceous of Montana |journal=Peabody Museum of Natural History Bulletin |volume=30 |pages=1–165}}</ref> However, one well – preserved specimen of ''Velociraptor mongoliensis'' (IGM 100/986) has an articulated tail skeleton that is curved laterally in a long S – shape. This suggests that, in life, the tail could bend from side to side with a substantial degree of flexibility.<ref name=norellmakovicky1999>{{cite_journal |last=Norell |first=Mark A. |coauthors=& Makovicky, Peter J. |year=1999 |title=Important features of the dromaeosaurid skeleton II: information from newly collected specimens of ''Velociraptor mongoliensis'' |journal=American Museum Novitates |volume=3282 |pages=1–45 |url=http://hdl.handle.net/2246/3025}}</ref> It has been proposed that this tail was used as a stabilizer and/or counterweight while running or in the air;<ref name=norellmakovicky1999/> in ''[[Microraptor]]'' and a possible specimen of ''[[Sinornithosaurus]]'' (specimen NGMC 91, nicknamed "Dave"), elongate diamond-shaped fans of feathers are preserved on the end of the tail. In ''Microraptor'', this may have been used as an aerodynamic stabilizer and rudder during gliding flight.<ref name="chatterjee2007">Chatterjee, S., and Templin, R.J. (2007). "Biplane wing planform and flight performance of the feathered dinosaur ''Microraptor gui''." ''Proceedings of the National Academy of Sciences'', '''104'''(5): 1576-1580. [http://www.pnas.org/cgi/reprint/0609975104v1.pdf]</ref><ref name="Qiang01">Ji, Q., Norell, M. A., Gao, K-Q., Ji, S.-A., Ren, D. (2001). "The distribution of integumentary structures in a feathered dinosaur." ''Nature'', '''410'''(6832): 1084 - 1088.</ref>
===Size===
Dromaeosaurids were small to medium-sized dinosaurs, ranging from about .6 meters in length (2 ft, in the case of ''Microraptor'') to over 6 m (20 ft, in ''[[Utahraptor]]'' and ''[[Achillobator]]'').<ref name="hwangetal2002">Hwang, S.H., Norell, M.A., Ji, Q., and Gao, K. (2002). "New Specimens of ''Microraptor zhaoianus'' (Theropoda: Dromaeosauridae) from Northeastern China." ''American Museum Novitates'', 3381: 44pp.[http://research.amnh.org/%7Esunny/hwang.et.al.2002.pdf]</ref><ref>Perle, A., Norell, M.A., and Clark, J. (1999). "A new maniraptoran theropod - ''Achillobator giganticus'' (Dromaeosauridae) - from the Upper Cretaceous of Burkhant, Mongolia." ''Contributions of the Mongolian-American Paleontological Project'', '''101''': 1–105.</ref>
The most primitive dromaeosaurid ever described, ''[[Mahakala (dinosaur)|Mahakala]]'', is also among the smallest, at just 70 cm long. This evidence, combined with the small size of other primitive relatives indicates that the common ancestor of dromaeosaurids, troodontids, and birds – which is called the ancestral paravian (‘’[[Paraves]]’’) – may have been very small, at around 65 cm in length and 600 to 700 grams of mass.<ref name="turneretal2007"/>
==Relationship with birds==
[[Image:Archaeo-deinony hands.svg|thumb|right|200px|Comparison of the forelimbs of ''[[Deinonychus]]'' (left) and ''[[Archaeopteryx]]'' (right), one of many skeletal similarities between avians and dromaeosaurids.]]
{{Details more|Origin of birds|Feathered dinosaurs}}
Dromaeosaurids share many features with early [[bird]]s. The precise nature of their relationship to birds has undergone a great deal of study, and hypotheses about that relationship have changed as large amounts of new evidence became available. As late as 2001, [[Mark Norell]] and colleagues analyzed a large survey of [[coelurosaur]] fossils and produced the tentative result that dromaeosaurids were most closely related to birds (clade [[Avialae]]), with [[troodontid]]s as a more distant outgroup. they even suggested that Dromaeosauridae could be paraphyletic relative to Avialae.<ref name=Norelletal01>Norell, M. Clark, J.M., Makovicky, P.J. (2001). "Phylogenetic relationships among coelurosaurian theropods." ''New Perspectives on the Origin and Evolution of Birds: Proceedings of the International Symposium in Honor of John H. Ostrom”, Yale Peabody Museum: 49-67.</ref> In 2002, Hwang and colleagues utilized the work of Norell ''et al.'', including new characters and better fossil evidence, to determine that birds (avialans) were better thought of as cousins to the dromaeosaurids and [[troodontid]]s.<ref name="hwangetal2002">Hwang, S.H., Norell, M.A., Ji, Q., and Gao, K. (2002). "New Specimens of ''Microraptor zhaoianus'' (Theropoda: Dromaeosauridae) from Northeastern China." ''American Museum Novitates'', 3381: 44pp.[http://research.amnh.org/%7Esunny/hwang.et.al.2002.pdf]</ref>
The current consensus among paleontologists agrees with the findings of Hwang ''et al'' (2002); that dromaeosaurids are most closely related to the troodontids, and together with the troodontids form the clade [[Deinonychosauria]]. Deinonychosaurians in turn are the [[sister taxon]] to birds, and therefore the closest non-avian relatives of birds.<ref name=senteretal2004>Senter, Phil, Barsbold, R., Britt, Brooks B. & Burnham, David B. (2004). "Systematics and evolution of Dromaeosauridae (Dinosauria, Theropoda)." ''Bulletin of the Gunma Museum of Natural History'' 8: 1–20.</ref> A consensus of paleontologists has concluded that there is not yet enough evidence to determine whether any dromaeosaurs could fly or glide, or whether they evolved from ancestors that could.<ref name=Padian05>Padian, K., and Dial, K.P. (2005). "Could 'four-winged' dinosaurs fly?" ''Nature'', '''438''' 17 November 2005: E3. doi:0.1038/nature04354</ref>
===Alternative theories and flightlessness===
Dromaeosaurids are so birdlike in some ways that they have led some researchers to wonder if they should be better classified as birds. First, since they have feathers, dromaeosaurs (along with many other coelurosaurian [[theropod]] dinosaurs) are “birds” under traditional definitions of the word “bird”, or “Aves”, that are based on the possession of feathers. Calling a primitive theropod like ''[[Caudipteryx]]'' a bird because it has feathers, however, may stretch the word past any useful meaning.<ref name=”Witmer02”>Witmer, L.M. (2005) “The Debate on Avian Ancestry; Phylogeny, Function and Fossils.” In “Mesozoic Birds: Above the Heads of Dinosaurs”, pp. 3-30. ISBN 0-520-20094-2</ref> (See the article [[Avialae]] for a discussion about the definitions of the clades Aves and Avialae.)
At least two schools of researchers have proposed that dromaeosaurs may actually be descended from flying ancestors. Hypotheses involving a flying ancestor for dromaeosaurs are sometimes called “[[Birds Came First]]” (BCF). [[George Olshevsky]] is usually credited as the first author of BCF.<ref name="Olshevsky94">Olshevsky, George. (1994). "The birds first? A theory to fit the facts - evolution of reptiles into birds". ''Omni'', June 1994. Volume 16 No. 9</ref> In his own work, Gregory S. Paul pointed out numerous features of the dromaeosaurid skeleton that he interpreted as evidence that the entire group had evolved from flying, dinosaurian, ancestors, perhaps something like ''[[Archaeopteryx]]''. In that case, the larger dromaeosaurids were secondarily flightless, like the modern [[ostrich]].<ref name=paul2002>Paul, Gregory S. (2002). ''Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds.'' Baltimore: Johns Hopkins University Press. 472 pp.</ref> In 1988, Paul suggested that dromaeosaurids may actually be more closely related to modern birds than to Archaeopteryx. By 2002, however, Paul placed dromaeosaurs and Archaeopteryx as the closest relatives to one another.<ref name=paul1988>Paul, Gregory S. (1988). ''Predatory Dinosaurs of the World.'' New York: Simon and Schuster. 464 pp.</ref>
In 2002, Hwang ''et al.'' found that ''Microraptor'' was the most primitive dromaeosaur.<ref name="hwangetal2002">Hwang, S.H., Norell, M.A., Ji, Q., and Gao, K. (2002). "New Specimens of ''Microraptor zhaoianus'' (Theropoda: Dromaeosauridae) from Northeastern China." ''American Museum Novitates'', 3381: 44pp.[http://research.amnh.org/%7Esunny/hwang.et.al.2002.pdf]</ref> Xu and colleagues in 2003 cited the basal position of ''Microraptor'', along with feather and wing features, as evidence that the ancestral dromaeosaur could glide. In that case the larger dromaeosaurs would be secondarily terrestrial - having lost the ability to glide later in their evolutionary history.<ref name="xuetal2003">{{cite journal |last=Xing |first=Xu |authorlink= |coauthors=''et al.'' |year=2003 |month= |title=Four-winged dinosaurs from China |journal=[[Nature (journal)|Nature]] |volume=421 |issue=6921 |pages=335–340 |doi=10.1038/nature01342 |url= |accessdate= |quote= }}</ref>
Other researchers, like [[Larry Martin]] believe that dromaeosaurs, along with all maniraptorans are not dinosaurs at all. Martin asserted for decades that birds were unrelated to maniraptorans, but in 2004 he changed his position, and now he agrees that the two are the closest of relatives. Martin believes that maniraptorans are secondarily flightless birds, and that birds evolved from non–dinosaurian archosaurs (or non-theropod dinosaurs in Czerkas' case), so that most of the species formerly called theropods would now not even be classified as dinosaurs.<ref name=Martin04>Martin, L.S. (2004). "A basal archosaurian origin for birds." ''Acta Geologica Sinica'', '''50'''(6): 978-990.</ref>
In 2005, Mayr and Peters described the anatomy of a very well preserved specimen of ''Archaeopteryx'', and determined that its anatomy was more like non-avian theropods than previously understood. Specifically, they found that ''Archaeopteryx'' had a primitive palatine, unreversed hallux, and hyper-extendable second toe. Their phylogenetic analysis produced the controversial result that ''[[Confuciusornis]]'' was closer to ''Microraptor'' than to ''Archaeopteryx'', making the Avialae a paraphyletic taxon. They also suggested that the ancestral paravian was able to fly or glide, and that the dromaeosaurs and troodontids were secondarily flightless (or had lost the ability to glide).<ref name="Mayr05">{{cite journal |last=Mayr |first=G |authorlink= |coauthors=''et al.'' |year=2005 |month= |title=A Well-Preserved ''Archaeopteryx'' Specimen with Theropod Features |journal=[[Science (journal)|Science]] |volume=310 |issue=5753 |pages=1483–1486 |doi=10.1126/science.1120331 |url= |accessdate= |quote=|pmid=16322455 }}</ref><ref name="Mayr06">{{cite journal |last=Mayr |first=G |authorlink= |coauthors=Peters, SD |year=2006 |month= |title=Response to comment on ‘A Well-Preserved ''Archaeopteryx'' Specimen with Theropod Features’ |journal=Science |volume=313 |issue= |pages=1238c |id= |url= |accessdate= |quote=|doi=10.1126/science.1130964 }}</ref> Corfe and Butler criticized this work on methodological grounds.<ref name="Corfe06">{{cite journal |last=Corfe |first=IJ |authorlink= |coauthors=Butler, RJ |year=2006 |month= |title=Comment on ‘A Well-Preserved ''Archaeopteryx'' Specimen with Theropod Features’ |journal= Science|volume=313 |issue=5791 |pages=1238b |doi=10.1126/science.1130800 |url= |accessdate= |quote=|pmid=16946054 }}</ref>
There has been a recent contradiction of these alternative scenarios. Turner and colleagues in 2007 described a new dromaeosaurid, ''[[Mahakala (dinosaur)|Mahakala omnogovae]]'', which they found to be the most basal and most primitive member of the Dromaeosauridae, more basal than ''Microraptor''. ''Mahakala'' had short arms and no ability to glide. Turner ''et al.'' also inferred that flight evolved only in the Avialae, and these two points suggest that the ancestral dromaeosaurid could not glide or fly. In cladistic analysis, the more primitive ''Mahakala'' suggests that the ancestral condition for dromaeosaurids is non-[[flight|volant]].<ref name=turneretal2007a>{{cite journal |last=Turner |first=Alan H. |coauthors= Pol, Diego; Clarke, Julia A.; Erickson, Gregory M.; and Norell, Mark |year=2007 |title=A basal dromaeosaurid and size evolution preceding avian flight |url= |journal=Science |volume=317 |pages=1378–1381 |doi=10.1126/science.1144066 |pmid=17823350 }}</ref>
==Systematics==
===Taxonomy===
The authorship of the family Dromaeosauridae is credited to W.D. Matthew and [[Barnum Brown]], who erected it as a subfamily (Dromaeosaurinae) of the now-defunct family Deinodontidae in 1922, containing only the new genus ''[[Dromaeosaurus]]''.<ref name="matthew&brown1922">Matthew, W. D., and Brown, B. (1922) "The family Deinodontidae, with notice of a new genus from the Cretaceous of Alberta." ''Bulletin of the American Museum of Natural History'', '''46''': 367-385.</ref> Dromaeosauridae, along with [[Troodontidae]], make up the infraorder [[Deinonychosauria]].
The subfamilies of Dromaeosauridae frequently shift in content based on new analysis, but typically consist of the following groups. A number of dromaeosaurids have not been assigned to any particular subfamily, often because they are too poorly preserved to be placed confidantly in [[phylogenetic]] analysis (see section ''Phylogeny'' below), or because they are basal relative to the primary subdivisions of Dromaeosauridae (''[[Mahakala (dinosaur)|Mahakala]]'', for example, is the most primitive known dromaeosaurid and falls outside any named sub-group). The most basal subfamily of dromaeosaurids is often found to be the Unenlagiinae.<ref name="turneretal2007">{{cite journal |last=Turner |first=A.S. |coauthors=Hwang, S.H.; and Norell, M.A. |year=2007 |title=A small derived theropod from Öösh, Early Cretaceous, Baykhangor Mongolia |journal=American Museum Novitates |volume=3557 |pages=1–27 |url=http://digitallibrary.amnh.org/dspace/bitstream/2246/5845/1/N3557.pdf |accessdate=2007-03-29 |doi=10.1206/0003-0082(2007)3557[1:ASDTFS]2.0.CO;2}}</ref> This enigmatic group is the most poorly-supported subfamily of dromaeosaurs and it is possible that some or all of its members belong outside of Dromaeosauridae. The larger, ground-dwelling members like ''[[Buitreraptor]]'' and ''[[Unenlagia]]'' show strong flight adaptations, although they were probably too large to 'take off'. One member of this group, ''Rahonavis'', is very small, with well-developed wings that show evidence of quill knobs (the attachment points for flight feathers) and it is very likely that it could fly. The next most primitive clade of dromaeosaurs is the Microraptoria. This group includes many of the smallest dromaeosaurs, which show adaptations for living in trees. All known dromaeosaur skin impressions hail from this group and all show an extensive covering of feathers and well-developed wings. Like the unenlagiines, some species may have been capable of active flight. The subfamily Velociraptorinae has traditionally included ''Velociraptor'', ''[[Deinonychus]]'', and ''[[Saurornitholestes]]'', and while the discovery of ''[[Tsaagan]]'' lent support to the this grouping, the inclusion of ''Saurornitholestes'' is still uncertain. The Dromaeosaurinae is usually found to consist of medium to giant-sized species, with generally box-shaped skulls (the other subfamilies generally have narrower snouts).
[[Image:Utahraptor BW.jpg|thumb|200px|right|''[[Utahraptor]]'', a dromaeosaurine.]]
[[Image:Bambiraptor.jpg|thumb|200px|right|''[[Bambiraptor]]'', a microraptorine.]]
[[Image:Unenlagia BW.jpg|thumb|200px|right|''[[Unenlagia]]'', an unenlagiine.]]
[[Image:Velociraptor BW.jpg|thumb|200px|right|''[[Velociraptor]]'', a velociraptorine.]]
The following classification of the various genera of dromaeosaurids is based on studies by Sereno (2005), Senter (2004), Makovicky ''et al.'' (2005), Norell ''et al.'' (2006), and Turner ''et al.'' (2007).<ref name="sereno2005">Sereno, P. C. 2005. [http://www.taxonsearch.org/Archive/stem-archosauria-1.0.php Stem Archosauria—TaxonSearch] [version 1.0, 2005 November 7]</ref><ref name="senteretal2004"/><ref name="makovickyetal2005">Makovicky, Peter J., Apesteguía, Sebastián & Agnolín, Federico L. (2005). The earliest dromaeosaurid theropod from South America. ''Nature'', 437: 1007–1011. {{doi|10.1038/nature03996}}</ref><ref name="norelletal2006">Norell, M.A., Clark, J.M., Turner, A.H., Makovicky, P.J., Barsbold, R., and Rowe, T. (2006). "A new dromaeosaurid theropod from Ukhaa Tolgod (Omnogov, Mongolia)." ''American Museum Novitates'', '''3545''': 1-51.</ref><ref name=turneretal2007a/>
* '''Family Dromaeosauridae'''
** ''[[Atrociraptor]]''
** ''[[Dromaeosauroides]]''
** ''[[Luanchuanraptor]]''
** ''[[Mahakala (dinosaur)|Mahakala]]''
** ''[[Pyroraptor]]''
** ?''[[Unquillosaurus]]''<ref name="novas&agnolin2004">Novas and Agnolin, (2004). "''Unquillosaurus ceibalii'' Powell, a giant maniraptoran (Dinosauria, Theropoda) from the Late Cretaceous of Argentina." ''Rev. Mus. Argentino Cienc. Nat.'', n.s. '''6'''(1): 61-66.</ref>
** ''[[Variraptor]]''
** '''Subfamily Dromaeosaurinae'''<ref name="matthew&brown1922"/>
*** ''[[Achillobator]]''
*** ''[[Adasaurus]]''
*** ''[[Dromaeosaurus]]''
*** ''[[Utahraptor]]''
** '''Subfamily Microraptorinae'''<ref name="senteretal2004"/>
*** ''[[Bambiraptor]]''
*** ''[[Cryptovolans]]''
*** ''[[Graciliraptor]]''
*** ''[[Microraptor]]''
*** ''[[Sinornithosaurus]]''
** '''Subfamily Unenlagiinae'''<ref name="bonapatre1999">Bonaparte, (1999).</ref>
*** ''[[Buitreraptor]]''
*** ''[[Neuquenraptor]]''
*** ''[[Rahonavis]]''
*** ''[[Shanag]]''
*** ''[[Unenlagia]]''
** '''Subfamily Velociraptorinae'''<ref name="barsbold1983">Barsbold, R. (1983). "O ptich'ikh chertakh v stroyenii khishchnykh dinozavrov. ["Avian" features in the morphology of predatory dinosaurs]." ''Transactions of the Joint Soviet Mongolian Paleontological Expedition'' '''24''': 96-103. [Original article in Russian.] Translated by W. Robert Welsh, copy provided by Kenneth Carpenter and converted by Matthew Carrano. [http://ravenel.si.edu/paleo/paleoglot/files/Barsbold_83b.pdf PDF fulltext]</ref>
*** ''[[Deinonychus]]''
*** ''[[Nuthetes]]''<ref name="sweetman2004">Sweetman, S.C. (2004). "The first record of velociraptorine dinosaurs (Saurischia, Theropoda) from the Wealden (Early Cretaceous, Barremian) of southern England." ''Cretaceous Research'', '''25'''(3): 353-364. doi:10.1016/j.cretres.2004.01.004</ref>
*** ''[[Saurornitholestes]]''
*** ''[[Tsaagan]]''
*** ''[[Velociraptor]]''
===Phylogeny===
Dromaeosauridae was first defined as a [[clade]] by [[Paul Sereno]] in 1998, as the most inclusive natural group containing ''Dromaeosaurus'' but not ''[[Troodon]]'', ''[[Ornithomimus]]'' or ''[[Passer]]''. The various "subfamilies" have also been re-defined as clades, usually defined as all species closer to the groups namesake than to ''Dromaeosaurus'' or any namesakes of other sub-clades (for example, Makovicky defined the clade Unenlagiinae as all dromaeosaurids closer to ''Unenlagia'' than to ''Velociraptor''). The Microraptoria is the only dromaeosaurid sub-clade not converted from a subfamily. Senter and colleagues expressly coined the name without the subfamily suffix ''-inae'' to avoid perceived issues with erecting a [[Linnean taxonomy|traditional]] family-group taxon, should the group be found to lie outside dromaeosauridae proper.<ref name="senteretal2004"/> Sereno offered a revised definition of the sub-group containing ''Microraptor'' to ensure that it would fall within Dromaeosauridae, and erected the subfamily Microraptorinae, attributing it to Senter ''et al.'', though this usage has only appeared on his online TaxonSearch database and has not been formally published.<ref name="sereno2005"/>
The [[cladogram]] below follows a 2007 analysis by Turner and colleagues, with sub-clades labelled according to definitions by Sereno, 2005.<ref name="turneretal2007b"/>
{{clade| style=font-size:100%;line-height:100%
|label1='''Dromaeosauridae'''
|1={{clade
|1=''[[Mahakala (dinosaur)|Mahakala]]''
|label2=<font color="white">unnamed</font>
|2={{clade
|label1=Unenlagiinae
|1={{clade
|1=''[[Shanag]]''
|2=''[[Buitreraptor]]''
|label3=<font color="white">unnamed</font>
|3={{clade
|1=''[[Rahonavis]]''
|2=''[[Unenlagia]]''
}}
}}
|label2=Microraptorinae
|2={{clade
|1=''[[Microraptor]]''
|2=''[[Graciliraptor]]''
}}
|3=''[[Sinornithosaurus]]''
}}
|label3=<font color="white">unnamed</font>
|3={{clade
|label1=Velociraptorinae
|1={{clade
|1=''[[Tsaagan]]''
|label2=<font color="white">unnamed</font>
|2={{clade
|1=''[[Saurornitholestes]]''
|label2=<font color="white">unnamed</font>
|2={{clade
|1=''[[Deinonychus]]''
|2=''[[Velociraptor]]''
}}
}}
}}
|label3=Dromaeosaurinae
|3={{clade
|1=''[[Adasaurus]]''
|2=''[[Dromaeosaurus]]''
|label3=<font color="white">unnamed</font>
|3={{clade
|1=''[[Achillobator]]''
|2=''[[Utahraptor]]''
}}
}}
}}
}}
}}
==Paleobiology==
===Predatory behavior===
[[Image:Dromaeosaurid foot NHM.jpg|thumb|right|Model of the "sickle claw" of a dromaeosaurid.]]
There is currently disagreement about the function of the enlarged "sickle claw" on the second toe. When John Ostrom described it for ''Deinonychus'' in 1969, he interpreted the claw as a blade-like slashing weapon, much like the canines of some [[Homotherium|saber-toothed cats]], used with powerful kicks to disembowel prey. This interpretation was commonly applied to all dromaeosaurids. However, Manning ''et al.'' argued that the claw instead served as a hook, reconstructing the keratinous sheath with an elliptical cross section, instead of the previously inferred inverted teardrop shape.<ref name="manningetal2005">{{cite journal | author = Manning, P.L., Payne, D., Pennicott, J., Barrett, P.M., and Ennos, R.A. | year = 2005 | title = Dinosaur killer claws or climbing crampons? | url = http://www.journals.royalsoc.ac.uk/openurl.asp?genre=article&eissn=1744-957X&volume=2&issue=1&spage=110 | journal = Biology Letters | volume = 2 | pages = 110–112 | doi = 10.1098/rsbl.2005.0395 }}</ref> In Manning's interpretation, the second toe claw would be used as a climbing aid when subduing bigger prey and also as stabbing weapon.
====Pack hunting and trackway====
''[[Deinonychus]]'' fossils have been uncovered in small groups near the remains of the herbivore ''[[Tenontosaurus]]'', a larger [[ornithischia]]n dinosaur. This had been interpreted as evidence that these dromaeosaurs hunted in coordinated packs like some modern [[mammal]]s.<ref name="maxwell&ostrom1995">{{cite journal|last=Maxwell|first=W. D.|coauthors=Ostrom, J.H.|year=1995|title=Taphonomy and paleobiological implications of ''Tenontosaurus''-''Deinonychus'' associations|journal=Journal of Vertebrate Paleontology|volume=15|issue=4|pages=707–712}}</ref> However, not all [[paleontologist]]s found the evidence conclusive, and subsequent studies suggest that the ''Deinonychus'' were more likely to have been engaged in disorganized [[mobbing behavior]]. Modern [[bird]]s and [[crocodile]]s (the closest relatives of dromaeosaurs) display little cooperative hunting; instead, they are usually either solitary hunters, or are drawn to previously-killed carcasses, where conflict often occurs between individuals of the same species. For example, in situations where groups of komodo dragons are eating together, the largest individuals eat first and will attack smaller komodos that attempt to feed; if the smaller animal dies, it is [[cannibalism (zoology)|cannibalized]]. When this information is applied to the sites containing putative pack-hunting behavior in dromaeosaurs, it appears consistent with a komodo- or crocodile-like feeding strategy. ''Deinonychus'' skeletal remains found at these sites are from subadults, with missing parts consistent with having been eaten by other ''Deinonychus'', evidence against the idea that the animals cooperated in the hunt.<ref>{{cite journal|last=Roach|first=B. T.|coauthors=D. L. Brinkman|year=2007|title=A reevaluation of cooperative pack hunting and gregariousness in ''Deinonychus antirrhopus'' and other nonavian theropod dinosaurs|journal=Bulletin of the Peabody Museum of Natural History|volume=48|issue=1|pages=103–138|doi=10.3374/0079-032X(2007)48[103:AROCPH]2.0.CO;2}}</ref>
In 2007, scientists described the first known extensive dromaeosaur [[fossil trackway|trackway]], in Shandong, China. In addition to confirming the hypothesis that the sickle-claw was held retracted off the ground, the trackway (made by a large, ''[[Achillobator]]''-sized species) showed evidence of six individuals of about equal size moving together along a shoreline. The individuals were spaced about one meter apart, and retained the same direction of travel, walking at a fairly slow pace. The authors of the paper describing these footprints interpreted the trackways as evidence that some species of dromaeosaurs lived in groups. While the trackways clearly do not represent hunting behavior, the idea that groups of dromaeosaurs may have hunted together could not be ruled out.<ref name="Lietal2007"/>
===Feathers===
[[Image:Microraptor gui (dinos).jpg|thumb|right|200px|Fossil of ''[[Microraptor|Microraptor gui]]'' with feather impressions.]]
There is a large body of evidence showing that dromaeosaurids were covered in [[feather]]s. Some dromaeosaurid fossils preserve long, pennaceous feathers on the hands and arms (''remiges'') and tail (''rectrices''), as well as shorter, down-like feathers covering the body.<ref name="xuetal1999"/><ref name=xuetal2003/> Other fossils, which do not preserve actual impressions of feathers, still preserve the associated bumps on the forearm bones where long wing feathers would have attached in life.<ref name="turneretal2007b"/> Overall, this feather pattern looks very much like ''[[Archaeopteryx]]''.<ref name=xuetal2003/>
The first known dromaeosaur with definitive evidence of [[feather]]s was ''[[Sinornithosaurus]]'', reported from [[China]] by Xu ''et al.'' in 1999.<ref name="xuetal1999">{{cite journal | author = Xu, X., Wang, X.-L., and Wu, X.-C. | date = 1999 | title = A dromaeosaurid dinosaur with a filamentous integument from the Yixian Formation of China <!-- | url = 404 error http://www.nature.com/nature/journal/v401/n6750/abs/401262a0_fs.html --> | journal = Nature | volume = 401 | pages = 262–266 | doi = 10.1038/45769 }}</ref> Many other dromaeosaurid fossils have been found with feathers covering their bodies, some with fully-developed feathered wings. Several even show evidence of a second pair of wings on the hind legs, including ''[[Microraptor]]'' and ''[[Cryptovolans]]''.<ref name=xuetal2003/> While direct feather impressions are only possible in fine-grained sediments, some fossils found in coarser rocks show evidence of feathers by the presence of quill knobs, the attachment points for wing feathers possessed by some birds. The dromaeosaurids ''Rahonavis'' and ''Velociraptor'' have both been found with quill knobs, showing that these forms had feathers despite no impressions having been found. In light of this, it is most likely that even the larger ground-dwelling dromaeosaurids bore feathers, since even flightless birds today retain most of their plumage, and relatively large dromaeosaurids, like ''Velociraptor'', are known to have retained pennaceous feathers.<ref name=paul2002/><ref name="turneretal2007b"/> Though some scientists had suggested that the larger dromaeosaurids lost some or all of their insulatory covering, the discovery of feathers in ''Velociraptor'' specimens has been cited as evidence that all members of the family retained feathers.<ref name="prum&brush2002">Prum, R., and Brush, A.H. (2002). "The evolutionary origin and diversification of feathers". ''The Quarterly Review of Biology'', '''77''': 261-295.</ref><ref name="turneretal2007b">{{cite journal |last=Turner |first=A.H. |coauthors=Makovicky, P.J.; and Norell, M.A. |year=2007 |title=Feather quill knobs in the dinosaur ''Velociraptor'' |journal=Science |volume=317 |issue=5845 |pages=1721|url=http://www.sciencemag.org/cgi/reprint/317/5845/1721.pdf |format=pdf |doi=10.1126/science.1145076 |pmid=17885130 }}</ref>
== In popular culture ==
{{Seealso|Biological issues in Jurassic Park}}
The dimensions of the supposed ''[[Velociraptor]]'' in the film [[Jurassic Park]] are much larger than the largest members of the genus. Robert Bakker recalled that Steven Spielberg had been disappointed with the dimensions of ''Velociraptor'' and so upsized it, adding that soon afterwards he named ''[[Utahraptor]]'' which was more the size depicted.<ref name=bakker1995>{{cite_book |last=Bakker |first=Robert T. |authorlink=Bob Bakker |year=1995 |title=Raptor Red |location=New York |publisher=Bantam Books |pages=pg. 4
|isbn=0-553-57561-9}}</ref> [[Gregory S. Paul]], in his book ''Predatory Dinosaurs of the World'', concluded that ''Deinonychus'' was a species of ''Velociraptor'' and rechristened the species ''Velociraptor antirrhopus'',<ref name="paul1988"/> a theory that has since been largely rejected.<ref name="perezetal">{{cite journal |last=Pérez-Moreno |first=B.P. |coauthors=J. L. Sanz, J. Sudre and B. Sigé |year=1994 |title=A theropod dinosaur from the Lower Cretaceous of southern France |journal=Dinosaurs and Other Fossil Reptiles of Europe, Second Georges Cuvier Symposium, Montbéliard; Revue de Paléobiologie, Volume spécial |volume=7 |pages=173–188}}</ref><ref name="currie">{{cite journal |last=Currie |first=P. J. |year=1995 |title=New information on the anatomy and relationships of ''Dromaeosaurus albertensis'' (Dinosauria: Theropoda) |journal=Journal of Vertebrate Paleontology |volume=15 |issue=3 |pages=576–591}} ([https://www.vertpaleo.org/publications/jvp/15-576-591.cfm abstract])</ref><ref name ="dinosauria04"/> [[Michael Crichton]] continued to [[synonymy|synonymize]] the two genera in his novels, on which the first two films were based. The depiction of the dromaeosaurid in the original ''Jurassic Park'' film, while accurate for its time, is now known to have been inaccurate in many respects, including the lack of [[Feathered dinosaurs|feathers]]. While ''[[Jurassic Park III]]'' attempted to address this last oversight by adding quill-like structures around the head of some of its dromaeosaurs, they did not resemble the structure or distribution of actual dromaeosaurid feathers known from fossil remains.
{{-}}<!--Do not remove: needed because, at higher resolutions, the Jurassic Park image causes the columned references to break.-->
== References ==
{{reflist}}
==External links==
{{Wikispecies|Dromaeosauridae}}
* [http://www.dinodata.org/index.php?option=com_content&task=view&id=1010&Itemid=104 Dromaeosauridae] at DinoData.
* [http://www.ucmp.berkeley.edu/diapsids/saurischia/dromaeosauridae.html The Dromaeosauridae: The Raptors!], from the University of California Berkeley Museum of Paleontology.
* [http://www.users.qwest.net/~jstweet1/dromaeosauridae.htm Dromaeosauridae], by Justin Tweet from ''Thescelosaurus''.
* [http://www.ageofdinosaur.com/index.htm Dinosaurs] - Complete and free online edition of the book "Dinosaurs" as written by W. D. Matthew (cited in this article with authorship of the family Dromaeosauridae), and former Curator of Vertebrate Paleontology at the American Museum of Natural History in New York; Originally published in 1915
* [http://www.dinosaur-world.com/feathered_dinosaurs/dromaeosauridae.htm Dromaeosauridae], Dinosaur-world reference with in-depth description and pictures of many dromaeosauridae dinosaurs
{{portalpar|Dinosaurs}}
[[Category:Dromaeosaurs| ]]
[[Category:Fossil trackways]]
[[ca:Dromaeosàurid]]
[[cs:Dromaeosauridae]]
[[da:Dromaeosauridae]]
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[[es:Dromaeosauridae]]
[[eo:Dromeosaŭredoj]]
[[fr:Dromaeosauridae]]
[[it:Dromaeosauridae]]
[[he:דרומאוזאוריים]]
[[lt:Dromaeosauridae]]
[[hu:Dromaeosauridae]]
[[ms:Dromaeosauridae]]
[[nl:Dromaeosauridae]]
[[pl:Dromeozaury]]
[[pt:Dromaeosauridae]]
[[simple:Dromaeosauridae]]
[[sk:Dromaeosauridae]]
[[fi:Dromaeosauridae]]
[[sv:Dromeosaurider]]
[[vo:Dromaeosauridae]]
[[zh:馳龍科]]